Cyclic Fatigue Properties of Titanium Alloys for Application in Dental Implants.

The present study investigated the cyclic fatigue properties of titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb) as implant materials and compared their properties with those of commercially pure titanium. Ti-6Al-4V and Ti-6Al-7Nb cylinders with diameters of 3.0 mm were examined. The surfaces of the cylinders were roughened by sand blasting with alumina particles and acid etching. Static and cyclic tests were performed according to ISO 14801:2016. The yield force in the static test (YS) was measured in 5 specimens of each alloy using a universal testing machine. The yield force in a cyclic test (YC) was measured in 20 specimens of each alloy using the staircase method, which involved applying a cyclic load at a frequency of 10 Hz for 106 cycles. After the cyclic loading tests, cross-sections of the specimens were examined under an optical microscope. The YS values for Ti-6Al-4V and Ti-6Al-7Nb were 1463 N±93 N and 1405 N±79 N, respectively, and the YC values were 870 N±58 N and 853 N±202 N, respectively. Microscopic observation revealed cracks on the tensile side of some of the specimens, including run outs and failures. The results of this study suggest that the YC values for Ti-6Al-4V and Ti-6Al-7Nb were 40% less than those for YS. The yield force of Grade-4 Cp-Ti significantly decreased after cyclic loading. The YC values for Ti-6Al-4V and Ti-6Al-7Nb were approximately 900 N, which was markedly greater than that for commercially pure, Grade-4 titanium (700 N).

Effect of elastic oral appliance chewing on frontal lobe activity.

OBJECTIVES: Chewing increases frontal lobe activity, resulting in improved memory, learning ability, and response reaction time. This study aimed to assess the effects of elastic oral appliance chewing on the activities and functions of the frontal lobe. METHODS: The study participants were 15 healthy men with full dentulous (mean age, 27.4 ± 4.1 years). A prospective crossover design was used to assess frontal lobe activities and functions. Changes in frontal lobe activities were measured with near-infrared spectroscopy (NIRS). At baseline, the participants were assessed in the resting state. Changes in channels #7, representing right frontal lobe activities by NIRS, and #10, representing left frontal lobe activities, during the first and second chewing periods in a total of two periods were evaluated. Frontal lobe functions were measured using the Trail Making Test Part A (TMT-A) in the resting state and after elastic oral appliance or gum chewing. These values were compared with each period. RESULTS: Elastic oral appliance chewing caused significant differences between the baseline and first chewing periods for channel #7 (p = .032) and significant differences between the baseline and second chewing periods for channels #7 and #10 (p < .001 and p < .001, respectively) using NIRS. Moreover, significant differences were found in the TMT-A results between the resting state and elastic oral appliance chewing (p = .04). CONCLUSIONS: Elastic oral appliance chewing improves frontal lobe activities to a level similar to that obtained with gum chewing.

Prosthodontic treatment can improve the ingestible food profile in Japanese adult outpatients.

PURPOSE: To investigate the effect of prosthodontic treatment on the ingestible food profile in adult Japanese outpatients, and to identify the related risk factors that can deteriorate the profile. METHODS: The participants were 277 outpatients who visited university-based specialty clinics in Japan for prosthodontic treatment. The demographic data, number of present teeth assessed via intraoral examination, and oral health-related quality of life assessed by the total Oral Health Impact Profile (OHIP-J54) scores of all participants were recorded before treatment. Ingestible food profile score (IFS) was recorded using a validated food intake questionnaire. Eligible participants who answered the questionnaire before and after treatment were categorized into five groups based on the prosthodontic treatments they received (i.e., crowns, bridges, removable partial dentures, removable complete dentures, and removable complete and partial dentures). RESULTS: Multivariate analysis of covariance revealed a statistically significant main effect of prosthodontic intervention (time course: before and after treatment) on mean IFS (P=0.035, F=4.526), even after adjusting for covariates (age, number of present teeth, and treatment modality). Multiple linear regression analysis revealed that the low number of present teeth (r=0.427, P<0.001) and a high OHIP-J54 total score (r=-0.519, P<0.001) of the patients at the baseline were significantly associated with their baseline IFSs, even after adjusting for confounding variables. CONCLUSIONS: The findings of this multicenter follow-up study indicate the importance of prosthodontic rehabilitation in improving patients' ingestible food profiles.

Radial versus femoral access in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: A propensity-matched analysis from real-world data of the K-ACTIVE registry.

BACKGROUND: The access site for primary percutaneous coronary intervention (PCI) for patients with ST-elevation myocardial infarction (STEMI) recently shifted from femoral to radial. However, few real-world data on Japanese patients exist. METHODS: To elucidate the clinical selection and impact of the access site in STEMI patients, we analyzed a Japanese observational prospective multicenter registry of acute myocardial infarction (K-ACTIVE: Kanagawa ACuTe cardIoVascular rEgistry) in 2015 to 2021. Data were analyzed in the entire population and a propensity score-matched population adjusted for confounding factors. Major adverse cardiac event (MACE) was defined as cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke. Bleeding Academic Research Consortium (BARC) type 3 or 5 was used to assess bleeding events. MACE plus BARC type 3 or 5 bleeding were considered composite events. Clinical outcomes were followed for 30 days. RESULTS: The 6802 STEMI patients included 4786 patients with radial access (70.3 %) and 2016 with femoral access (29.7 %). Femoral access tended to be selected for more severe conditions than radial access. The median door-to-device time in the radial access group was significantly shorter than the femoral access group in the entire population (75 min versus 79 min, p < 0.01). After propensity score matching (each group, n = 1208), the incidence of MACE tended to be lower in the radial access group [risk ratio (RR) 0.83, 95 % confidence interval (CI) 0.63-1.09, p = 0.17]. The incidence of BARC 3 or 5 bleeding was significantly less in the radial access group (RR 0.47, 95%CI 0.23-0.97, p = 0.04). The incidence of composite events was significantly less in the radial access group (RR 0.74, 95%CI 0.57-0.96, p = 0.02). CONCLUSION: In STEMI patients undergoing primary PCI, in comparison to femoral access, radial access reduced composite events in the entire population and the matched population, through a reduction in MACE and BARC 3 or 5 bleeding.

Successful visualization of pulmonary embolism using fluoroscopic video analysis in a patient with iodine contrast allergy: a case report.

Background: Contrast-enhanced computed tomography (CT) is commonly used to diagnose pulmonary embolism (PE). However, a history of iodine contrast allergy presents a dilemma in the management of patients with PE. As an alternative approach, X-ray fluoroscopic video analysis has been recently reported to be useful in diagnosing PE. Case summary: A 78-year-old man with dyspnoea of 1-month duration visited our hospital. His oxygen saturation was 89%, and echocardiography demonstrated right heart strain. We could not perform contrast-enhanced CT because the patient had a history of contrast allergy and refused to undergo premedicated contrast CT with anti-histamine and/or corticosteroid. Therefore, a video analysis of pulmonary circulation using dynamic chest X-ray (DCR) was performed. The reconstructed pseudo-colour video showed defects of pulmonary circulation in both lung areas. We diagnosed PE and started anticoagulant therapy. Multiple segmental defects were also observed in pulmonary perfusion scintigraphy on Day 3, which confirmed the diagnosis of PE. He was discharged on Day 9, and an improvement of the pulmonary circulation as assessed with DCR was observed. He had no symptoms at the last follow-up visit at 1 year after discharge. Discussion: We describe the successful visualization of PE using DCR in a patient with iodine contrast allergy.

Relationship between two pressure-sensitive films for testing reduced occlusal force in diagnostic criteria for oral hypofunction.

OBJECTIVE: To measure the occlusal force in the same group of patients with the Dental Prescale 50H type R and the Dental Prescale II, examine the association between them, and determine the reference value for Dental Prescale II that corresponds to the 50H type R 200 N reference value used to make a diagnosis of oral hypofunction. BACKGROUND: Reduced occlusal force, a measure of frailty in older persons, was previously determined with Prescale 50H type R pressure-sensitive film, but it has been replaced by the Prescale II. MATERIALS AND METHODS: The study participants were 441 men and women aged ≥ 65 (mean, 71.8 ± 5.3) years. The occlusal force was measured with the two different types of pressure-sensitive film, and their association was examined. Receiver operating characteristic curves for the Prescale II measured values were created with the 200 N reference value used for the 50H type R film as the cut-off value. RESULTS: The analysis set included 391 participants for whom measurements were obtained using both the 50H type R and the Prescale II. Linear regression analysis produced regression equations, and a ROC curve analysis provided reference values of 500 N for the Prescale II (without pressure filter) and 350 N for the Prescale II (with pressure filter). CONCLUSION: In occlusal force tests for making a diagnosis of oral hypofunction, reference values for the Prescale II (without pressure filter) and for the Prescale II (with pressure filter) were determined. The findings suggested that the Prescale II can be used as a diagnostic examination for oral hypofunction.

Oral function is associated with the body and muscle mass indices of middle-aged dental patients.

OBJECTIVES: Undernutrition is associated with frailty, one of the common reasons for seeking long-term care. In older adults, nutritional status is known to be associated with oral function; however, it is not yet known if there is a similar association in middle-aged adults. The present study determined the association between nutritional status and oral function in middle-aged adults. MATERIAL AND METHODS: This cross-sectional study was conducted in 117 outpatients aged 40-64 years who underwent dental check-up at a private dental clinic. Factors associated with oral function, including oral moisture, number of teeth present, oral diadochokinesis, tongue pressure, lip-seal strength, and masticatory performance, were evaluated. Body mass index (BMI), fat-free mass index (FFMI), and skeletal muscle mass index (SMI) were analyzed as nutritional statuses. Pearson's correlation analysis was conducted to determine the correlation between nutritional statuses and other variables. Multiple linear regression analysis was performed, with adjustment for age and sex, using BMI, FFMI, or SMI as response variables and oral moisture, maximum tongue pressure, lip-seal strength, oral diadochokinetic rate, and masticatory performance as explanatory variables. RESULTS: All nutritional statuses showed significant correlation with maximum tongue pressure and lip-seal strength. Multiple linear regression analysis revealed that BMI was associated with maximum tongue pressure and lip-seal strength, whereas FFMI and SMI showed significant association with sex, maximum tongue pressure, and lip-seal strength. CONCLUSIONS: In middle-aged outpatients at a regional dental clinic, lip-seal strength and tongue pressure were positively associated with BMI, FFMI, and SMI.

Effect of Lip-seal Resistance Training on Lip-seal Strength in Young Adults.

Lip-seal strength is important for articulating bilabials, capturing food during eating, maintaining fluid within the oral cavity before swallowing, and achieving swallowing pressure. The objective of this study was to investigate the effect of lip-seal resistance training on lip-seal strength in young adults. The participants comprised 15 young healthy adults aged 26-34 years, all with complete dentition. Each was required to perform lip-seal resistance training 5 weekdays a week for 4 weeks with a commercially available instrument for that purpose. The instrument was placed on the midline, left corner, and right corner of the mouth, and pulled forward, leftward, and rightward, respectively. The participants were required to pull the training instrument forcefully while resisting by closing the lips together as strongly as possible until the instrument exited the lips. Lip-seal strength was measured at before and after training using a measurement device. Change in lip-seal strength between before and after training was analyzed using the Wilcoxon signed rank test. The mean lip-seal strength was 8.9±1.5 N before training and 10.4±1.8 N after. A significant difference was observed in lip-seal strength between before and after training (p=0.003), and the mean increase during the training period was 18.1±17.6%. The results showed that lip-seal resistance training for 4 weeks increased lip-seal strength in young adults. These findings suggest that training that involves pulling not only in a forward direction, but also in bilateral directions strongly stimulates the orbicularis oris muscle, resulting in an increase in lip-seal strength.

Distribution of lip-seal strength and its relation to oral motor functions.

OBJECTIVES: Lip-seal strength, which represents the muscle strength of the lips, appears to chiefly contribute to mastication and pronunciation. However, the functional characteristics of lip-seal strength in adults are still undefined. The present study aimed to understand not only the distribution of lip-seal strength in adult men and women but also the effect of age on this strength and identify oral motor functions correlated with lip-seal strength. MATERIALS AND METHODS: The subjects included 339 participants (men: 170, age 39.2 ± 18.2 years; women: 169, age 43.1 ± 19.7 years). Oral motor function was evaluated for lip-seal strength, oral diadochokinesis (ODK), tongue pressure, occlusal force, and masticatory performance. Statistical analyses included the Shapiro-Wilk, Mann-Whitney U, and Jonckheere-Terpstra tests, in addition to the Spearman's correlation analysis and curvilinear regression analysis. RESULTS: Lip-seal strength did not have a normal distribution (p < 0.001). The mean ± standard deviation and median (first quartile, third quartile) of lip-seal strength were 11.2 ± 3.4 and 10.9 (8.7, 13.2)N for the whole sample, 12.3 ± 3.4 and 11.9 (9.4, 14.4)N for men, and 10.2 ± 3.0 and 9.9 (8.0, 12.0)N for women. A significant difference was observed in lip-seal strength between men and women (p < 0.001). Oral motor functions showed a marked correlation with lip-seal strength, including tongue pressure, occlusal force, and masticatory performance and ODK (/pa/ and /ta/), tongue pressure, and masticatory ability in men and women, respectively. In women, lip-seal strength declined with increase in age. CONCLUSIONS: Lip-seal strength was non-normally distributed in both men and women, and lip-seal strength was affected by age only in women. Lip-seal strength and multiple oral motor functions were significantly correlated. Because the indicators of perioral muscle strength and performance were correlated with lip-seal strength, lip-seal strength may also partially reflect the condition of the perioral muscles.

An Interprofessional Approach to Oral Hygiene for Elderly Inpatients and the Perception of Caregivers Towards Oral Health Care.

OBJECTIVE: The objective of this study was to investigate the effect of an interprofessional oral hygiene support program for elderly inpatients and the perception of caregivers of the elderly towards oral health care. MATERIALS AND METHODS: Participants comprised 37 elderly inpatients requiring nursing care (17 males, 20 females; mean age, 83.3 ± 4.9 years) and 29 registered nurses who participated in the interprofessional oral health care support program as a caregiver (4 males, 25 females; mean age, 45.2 ± 10.3 years). In this program, inpatients received daily oral cleaning by registered nurses based on each patient's oral health care plan. The number of microbes on the tongue surface of the inpatients was measured once a week for 12 weeks. Additionally, as an investigation of the perception of the caregivers towards oral health care, a questionnaire about the required frequency and duration for oral cleaning was conducted with registered nurses before and after the program to investigate the perception of the caregivers towards oral health care. RESULTS: Significant differences were observed in the number of microbes on the tongue surface between baseline and at every measurement after the beginning of this program, except for the first week. The mean required frequency and duration for oral cleaning by registered nurses at baseline were 1.5 ± 0.8 times and 3.8 ± 2.2 minutes, whereas those after the program were 2.7 ± 0.7 times and 5.8 ± 2.9 minutes, respectively. CONCLUSION: Implementation of the program decreased the number of microbes on the tongue surface of the elderly inpatients and improved the perception of their caregivers towards oral health care.

Effective training duration and frequency for lip-seal training in older people using a self-training instrument.

OBJECTIVE: To determine the effects of the training duration and frequency on lip-seal strength (LSS) in older people. BACKGROUND: Lip-seal is important for speaking, eating and swallowing. LSS decreases after training ends; therefore, continuous training is essential. MATERIALS AND METHODS: Participants underwent the resistance training of LSS. Regarding training duration, eight women aged ≥65 years participated in a crossover study with trainings A (direction: 1, duration: 50 seconds) and B (directions: 3, duration: 3 minutes), daily for 4 weeks. Regarding training frequency, 40 women aged ≥65 years were divided into four groups based on frequency (everyday, every-other-day, once-a-week and control groups), and all groups excluding the control group performed training B for 4 weeks. LSS was measured at weeks 0, 2 and 4 using a digital strain gauge. Friedman's test was used, followed by Steel-Dwass test (α = 0.05). RESULTS: Regarding the effects of the training duration, significant differences in LSS were noted between weeks 0 and 4 for training B, but no difference was noted for training A. Regarding training frequency, significant differences were observed between weeks 0 and 2 or 4 in the everyday and once-a-week groups. Significant differences were observed in the every-other-day group between weeks 0 and 4 and no difference in the control group. For all groups, median LSS was higher in week 2 or 4 than that in week 0. CONCLUSION: Lip-seal training for 3 minutes per session everyday, every-other-day or once-a-week for 4 weeks increased LSS of older people.

Active sites of human MEPE-ASARM regulating bone matrix mineralization.

The proteolytic fragment ASARM (acidic serine- and aspartate-rich motif) of MEPE (matrix extracellular phosphoglycoprotein) (MEPE-ASARM) may act as an endogenous anti-mineralization factor involved in X-linked hypophosphatemic rickets/osteomalacia (XLH). We synthesized MEPE-ASARM peptides and relevant peptide fragments with or without phosphorylated Ser residues (pSer) to determine the active site(s) of MEPE-ASARM in a rat calvaria cell culture model. None of the synthetic peptides elicited changes in cell death, proliferation or differentiation, but the peptide (pASARM) with three pSer residues inhibited mineralization without causing changes in gene expression of osteoblast markers tested. The anti-mineralization effect was maintained in peptides in which any one of three pSer residues was deleted. Polyclonal antibodies recognizing pASARM but not ASARM abolished the pASARM effect. Deletion of six N-terminal residues but leaving the recognition sites for PHEX (phosphate regulating endopeptidase homolog, X-linked), a membrane endopeptidase responsible for XLH, intact and two C-terminal amino acid residues did not alter the anti-mineralization activity of pASARM. Our results strengthen understanding of the active sites of MEPE-pASARM and allowed us to identify a shorter more stable sequence with fewer pSer residues still exhibiting hypomineralization activity, reducing peptide synthesis cost and increasing reliability for exploring biological and potential therapeutic effects.

Cardiac tamponade due to ruptured coronary-pulmonary artery fistula aneurysm: a case report.

BACKGROUND: Coronary artery fistulas are rare and most commonly asymptomatic; however, they can become enlarged and rupture in some cases. CASE SUMMARY: We report a case of a 51-year-old woman who was brought to our hospital unconscious in an ambulance. Cardiac tamponade caused by the rupture of an aneurismal coronary-pulmonary artery fistula (CPAF) was detected by contrast-enhanced computed tomography and confirmed by invasive coronary angiography. Due to prompt diagnosis and subsequent surgical intervention, the patient's condition was rapidly improved, and she was discharged from the hospital. DISCUSSION: Coronary-pulmonary artery fistula aneurysm rupture requires rapid diagnosis and treatment, and thus, in cases with cardiac tamponade and coronary aneurysm, CPAF aneurysm rupture should be considered.

Rate of oral frailty and oral hypofunction in rural community-dwelling older Japanese individuals.

OBJECTIVE: To clarify the rate of oral frailty and oral hypofunction in rural community-dwelling older adults in Japan. BACKGROUND: Recently, the oral function of Japanese older adults has been evaluated multilaterally based on two concepts: oral frailty and oral hypofunction. Oral frailty is defined as a decrease in the oral function accompanied by a decrease in mental and physical functions. Oral hypofunction is a disease where the oral function is comprehensively decreased. However, their rates have not yet been elucidated. MATERIALS AND METHODS: Oral frailty and oral hypofunction were evaluated in 679 older adults from rural areas. To investigate the differences in occurrence rates due to the evaluation methods, one of the subordinate symptoms of oral hypofunction, the reduced occlusal force, was evaluated based on both the occlusal force (main method) and the number of teeth (alternative method). RESULTS: The rate of oral frailty was 22.3% in men and 22.7% in women. The rate of oral hypofunction was 39.0% in men and 46.9% in women. The overall rate of oral hypofunction was 43.6% when the reduced occlusal force of oral hypofunction was evaluated using the main method and 46.4% when evaluated using the alternative method. The proportion of participants with decreased occlusal force, the number of present teeth, oral diadochokinesis, tongue pressure and masticatory performance increased with age in both men and women. CONCLUSION: Among rural community-dwelling older adults, the rate of oral frailty was 22.5% and that of oral hypofunction was 43.6%.

Factors associated with masticatory performance in community-dwelling older adults: A cross-sectional study.

BACKGROUND: Decreased masticatory performance leads to deterioration of overall health among older adults. However, maintaining and improving masticatory performance in ways other than maintenance of natural teeth and appropriate prosthodontic treatment remains unclear. If the factors related to the mixing and shearing abilities for masticatory performance are clarified, it may be possible to maintain and improve the masticatory performance of older adults. We aimed to clarify the association among mixing ability, shearing ability, and masticatory performance-related factors. METHODS: Of the 707 community-dwelling older adults in Kusatsu Town, Japan, 344 who had been treated for any dental defects were enrolled in this study. Masticatory performance was evaluated on the basis of mixing ability and shearing ability. The number of natural teeth and artificial teeth, occlusal force, tongue pressure, and oral diadochokinesis /ta/ were measured as masticatory performance-related factors. Their relationship with mixing ability, shearing ability, and masticatory performance-related factors was examined by means of Spearman rank correlation coefficient and path analysis. RESULTS: Among masticatory performance-related factors, the number of natural teeth, occlusal force, and tongue pressure were directly associated with both mixing ability and shearing ability. Moreover, mixing ability was also directly associated with shearing ability. CONCLUSIONS: Tongue pressure, which can be improved by means of training, is a masticatory performance-related factor associated with both mixing and shearing abilities. PRACTICAL IMPLICATIONS: Training for tongue pressure after proper prosthetic treatment may provide an effective means of maintaining and improving masticatory performance in older adults.

Retention force and allowable range of the angle of an implant-supported overdenture attachment system using healing screws and a silicone resilient denture liner.

STATEMENT OF PROBLEM: Changes in the intraoral condition immediately after implant placement and in patients using fixed prosthetic appliances with implant abutments cause problems that require the use of an easily adjustable implant-supported overdenture system. PURPOSE: The purpose of this in vitro study was to develop a simulated implant-supported overdenture attachment system by using healing screws for the patrix and a silicone resilient denture liner for the matrix and to investigate the initial retention force, time-course changes, and allowable range of the angle between attachments. MATERIAL AND METHODS: Tests on the retention force and allowable range of the angle were performed. Attachments using tissue-level healing screws (height: 2.0 and 3.0 mm) for the patrix and a silicone resilient denture liner for the matrix were prepared. In the retention force measurement test, the frequency of insertion and removal was set at 3 per day to simulate a 4-month relief period. The joined attachment model was pulled apart, and the maximum traction (N) required to remove it was defined as the retention force. The retention force was measured every 90 times (representing the number of insertions and removals per month). To test the allowable angle range, 2 patrices were used. The angle between the 2 patrices was set at 0, 10, 20, and 30 degrees, and the angular limit for joining with the matrix was measured. The initial retention force of the healing screw attachments was compared with that of a polymeric O-ring by using 1-way layout ANOVA followed by the Bonferroni test (α=.05). To analyze time-course changes in the 2 types of healing screw attachments, the retention force before insertion and removal was compared with that after repeated insertions and removals for each simulated period using 1-way layout ANOVA followed by the Dunnett test (α=.05). RESULTS: The initial retention force of the 2.0- and 3.0-mm healing screws was 2.4 ±0.1 and 2.6 ±0.2 N. After repeating insertions and removals to simulate use for 4 months, the retention force of the 2.0- and 3.0-mm healing screws was 1.8 ±0.2 and 2.2 ±0.1 N, respectively, both showing significant differences from the initial retention force (P<.05). The allowable angle range test revealed that insertion and removal of the healing screws was possible up to 30 degrees. CONCLUSIONS: Under the conditions of this in vitro study, repeated insertion and removal attenuated the retention force but was still equivalent to the retention force of the O-ring. The allowable range of the angle between patrices for insertion and removal was up to 30 degrees.

Intra- and inter-investigator reliabilities of oral moisture measured using an oral moisture-checking device.

BACKGROUND: Oral mucosal moisture determined using oral moisture-checking devices is used as a mouth dryness evaluation method. Such devices are capable of evaluating the state of mouth dryness in a simple manner and have applicability in a wide range of subjects; however, their intra- and inter-investigator reliabilities have not yet been clarified. OBJECTIVE: This study aims to investigate the intra- and inter-investigator reliabilities of measuring oral moisture using an oral moisture-checking device for a wide range of age groups. METHODS: Intra- and inter-investigator reliabilities were investigated in 28 young subjects and 19 older subjects aged ≥65 years. Three trained investigators independently measured oral mucosal moisture values using an oral moisture-checking device. Intra-investigator reliability was assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) (1.1), and inter-investigator reliability was assessed using ICC (2.1). RESULTS: Mean CV was 0.015 and 0.016, mean ICC (1.1) was 0.806 and 0.877, and ICC (2.1) was 0.873 and 0.829 in the young and older subjects, respectively. CONCLUSION: In young subjects, the mean values of ICC (1.1) and ICC (2.1) of the oral moisture-checking device were 0.806 and 0.873, respectively, whereas in older subjects, these values were 0.877 and 0.829, respectively. Thus, this confirms that the examination of oral mucosal moisture using the oral moisture-checking device has sufficient intra- and inter-investigator reliabilities for a wide range of age groups.

Effect of mechanical and chemical cleaning on surface roughness of silicone soft relining material.

PURPOSE: This study aims to investigate the effect of mechanical and chemical cleaning on the surface roughness of silicone soft relining materials. METHODS: We selected silicone soft relining materials with the highest (Soft) and lowest (Supersoft) Shore A hardness. In the abrasion test, specimens were cleaned 50,000 times using a kitchen sponge (Sponge), a soft (Soft brush) or hard (Hard brush) denture brush, or stored in water (No cleaning). In the immersion test, specimens were immersed in either water (Water), neutral peroxide denture cleanser (Neutral), alkaline peroxide denture cleanser (Alkaline), or hypochlorite denture cleanser (Hypochlorite) for 1440 h. Surface roughness of the arithmetic mean height of the surface (Sa) and maximum height (Sz) were measured before and after the tests. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: In the abrasion test, significant differences were observed for Sa and Sz with Soft relining materials, but not for No cleaning and Sponge. In the immersion test, significant differences were observed for Sa and Sz with Soft relining materials, but not between Water and Neutral or Water and Alkaline. Significant differences were observed with Supersoft, except between Water and Neutral or Water and Alkaline for Sa and between Water and Neutral for Sz. CONCLUSIONS: Mechanical cleaning using a sponge did not increase the surface roughness of the material with a high Shore A hardness. Furthermore, neutral peroxide denture cleanser did not increase the roughness of materials with high and low Shore A hardness.

Comparison of adhesiveness of chewing gum to hard and soft denture base materials.

PURPOSE: The purpose of this study was to compare the adhesiveness of chewing gum to hard and soft denture base materials to investigate food retention associated with the basal surface of the denture. METHODS: Test specimens were fabricated using acrylic resin[Re], cobalt-chromium alloy[Co], zirconia[Zr], silicone soft relining material[SS], and acrylic soft relining material[AS]. Samples were set on a top-and-bottom pair lifting platform equipped with a digital force gauge. The experimenter chewed 3.0 g of chewing gum for 5 min. After surface saliva was wiped off, the chewing gum was placed on the lower test fragment and compressed until the distance between the upper and lower test fragments decreased to 1 mm. The upper test fragment was pulled at a crosshead speed of 100 mm/min. Adhesiveness was measured under dry conditions, and under wet conditions with inter-positioned artificial saliva. RESULTS: Under dry conditions, the adhesive strength was 17.04 ±â€¯1.99 N for Re, 12.88 ±â€¯2.20 N for Co, 3.80 ±â€¯1.03 N for Zr, 5.76 ±â€¯1.41 N for SS, and 12.54 ±â€¯2.44 N for AS. Under wet conditions, the adhesive strength was 5.26 ±â€¯1.64 N for Re, 0.96 ±â€¯0.21 N for Co, 3.32 ±â€¯0.40 N for Zr, 5.20 ±â€¯1.35 N for SS, and 6.78 ±â€¯1.97 N for AS. CONCLUSIONS: Among the hard denture base materials, zirconia recorded low adhesiveness and Re recorded high adhesiveness under both wet and dry conditions. The adhesiveness of Co was low under wet conditions but high under dry conditions. Among the soft denture base materials, SS under dry conditions recorded lower adhesiveness than that of AS. The adhesiveness of SS was low under both wet and dry conditions.

Applying intraoral scanner to residual ridge in edentulous regions: in vitro evaluation of inter-operator validity to confirm trueness.

BACKGROUND: The purpose of this study was to investigate the trueness of intraoral scanning of residual ridge in edentulous regions during in vitro evaluation of inter-operator validity. METHODS: Both edentulous maxillary and partially edentulous mandibular models were selected as a simulation model. As reference data, scanning of two models was performed using a dental laboratory scanner (D900, 3Shape A/S). Five dentists used an intraoral scanner (TRIOS 2, 3Shape A/S) five times to capture intraoral scanner data, and the "zig-zag" scanning technique was used. They did not have experience with using intraoral scanners in clinical treatment. The intraoral scanner data was overlapped with the reference data (Dental System, 3Shape A/S). Regarding differences that occurred between the reference and intraoral scanner data, the vertical maximum distance of the difference and the integral value obtained by integrating the total distance were analyzed. RESULTS: In terms of the maximum distances of the difference on the maxillary model, the means of five operators were as follows: premolar region, 0.30 mm; molar region, 0.18 mm; and midline region, 0.18 mm. The integral values were as follows: premolar region, 4.17 mm2; molar region, 6.82 mm2; and midline region, 4.70 mm2. Significant inter-operator differences were observed with regard to the integral values of the distance in the premolar and midline regions and with regard to the maximum distance in the premolar region, respectively. The maximum distances of the difference in the free end saddles on mandibular model were as follows: right side, 0.05 mm; and left side, 0.08 mm. The areas were as follows: right side, 0.78 mm2; and left side, 1.60 mm2. No significant inter-operator differences were observed in either region. CONCLUSIONS: The present study demonstrated satisfactory trueness of intraoral scanning of the residual ridge in edentulous regions during in vitro evaluation of inter-operator validity.